Revolvable chair



Sept. 25, 1956 K. MISCHKE REVOLVABLE CHA-IR Filed Aug. 24, 1954 Fig 1Fig.3

United States Patent O 2,764,223 REVOLVABLE CHAIR Karl Mischke, Zurich,Switzerland Application August 24, 1954, Serial No. 451,810 Claimspriority, application Switzerland August 25, 1953 3 Claims. (Cl. 155-95)The present invention relates to a swivel or revolving chair, which ischaracterized by the provision of a locking device, arranged between theseat and the support for the latter, and adapted to lock the seatagainst rotation when the latter is not loaded and to be automaticallyreleased when the seat is loaded.

The prime object of the invention is to obtain a swivel chair which isfreely revolvable when in use, but the seat of which is immediatelylocked in its last angular position with respect to the support when theuser of the chair stands up.

According to a preferred embodiment of the invention there is providedat least one locking pin connected with the seat and adapted toco-operate with one of a ring of stop grooves provided at the supportfor the seat, wherein spring means arranged between the seat and itssupport are adapted to maintain the said locking pin in engagement withone of the stop grooves as long as the seat is not loaded, while saidlocking pin comes out of engagement with said groove as soon as the seatis loaded thereby permit-ting free revolving of the latter with respectto its support.

Other features and advantages of the invention will become apparent fromthe description now to follow, of a preferred embodiment thereof,reference being had to the accompanying drawings showing the partsnecessary for the understanding of the invention and in which:

Fig. 1 is an elevational view of the not loaded and thus disengagedlocking device;

Fig. 2 is an elevational view of the locking device in locking position;

Fig. 3 illustrates the locking device as seen from the right hand sideof Fig. 2, and

Fig. 4 is a plan view of Fig. 2 with a central tube shown in section.

The support for the seat 2a is indicated by the upper portion of itscentral hollow column 1 receiving a rod 2 rigidly connected with theseat 2a. The seat is revolvable and adjustable in height with respect toits support owing to the arrangement of rod 2 in the column 1. The rod 2is provided with an axially adjustable clamping piece 3 fixed in thedesired position by means of a set screw 4 operable by a lever 5a fixedto a nut 5 and having a hole therein to accommodate screw 4 onto whichit is threaded. The square-shaped clamping piece 3 carries on twoopposite sides a pair of downwardly directed jaws 6 and 7 having each,on their sides facing each other, a cylindrical locking pin 6a and 7a,respectively. The arrangement would of course also work satisfactorilyif only one such jaw and locking pin would be provided. A ring 8, havinga square cross section, is fixed to the upper end of the column 1 and isprovided on its lower surface with a plurality of radially directed stopgrooves 8a adapted to cooperate with the mentioned locking pins 6a and7a. When the said pins 6a and 7a engage a pair of the said stop grooves,for example as shown in Fig. 2 and 3, the seat of the chair is lockedagainst undesired swivelling with respect to its support.

A strong, band-shaped helical spring 9 is arranged about the rod 2between the ring 8 and the clamping piece 3.

2,764,223 Patented Sept. 25, 1956 Upon a loading of the seat, as itoccurs for example when a person sits down on the chair, the seat isforced downwardly against the action of spring 9 so that the lockingpins 6a and 7a, which follow the movement of the seat, come out ofengagement with the stop grooves 8a of the ring 8 rigidly connected withthe column 1 and the seat may be revolved by the user with respect toits support, i. e. the column 1. As soon as the user of the chair standsup the seat is lifted under the action of the spring 9 and the lockingpins may again engage a pair of stop grooves of the ring 8. According tothe position of the seat at the moment the user stands up a slightrevolving movement may be necessary to bring the pins into engagementwith the grooves as is easily understandable.

A nut 10 is rigidly connected with the jaw 7 of the clamping piece 3.This nut 10 is adapted to receive a set screw 11, which is not shown inFigs. 1 and 3, and which, when the seat is not loaded, lies in the planeof the ring 8 of the column 1. Screwing of this screw 11 results in itsforward end being pressed against the upper portion of the ring 8 sothat the seat may be secured against rotation with respect to itssupport, i. e. to the column 1.

I claim:

1. In a swivel chair, a tubular support, a supporting rod for the seatarranged in said tubular support so as to be revolvable with respect tothe latter, a ring of stop grooves fixed to the support, a clampingpiece, axially adjustable on said supporting rod and having a downwardlyextending jaw, a locking pin provided on said jaw and adapted tocooperate with said stop grooves, and spring means arranged between theclamping piece and the ring for maintaining the locking pin engaged inone of said stop grooves when the seat is not used and permittingdisengaging of said pin out of the groove when the seat is loaded.

2. In a swivel chair, a tubular support, a supporting rod for the seatarranged in said tubular support so as to be revolvable with respect tothe latter, a ring of stop grooves fixed to the support, a clampingpiece, axially adjustable on said supporting rod and having a downwardlyextending jaw, a locking pin provided on said jaw and adapted tocooperate with said stop grooves, and spring means arranged between theclamping piece and the ring for maintaining the locking pin engaged inone of said stop grooves when the seat is not used and permittingdisengagement of said pin out of the groove when the seat is loaded, anda set screw on said jaw adapted to engage said ring of stop grooves forlocking the seat in any angular position with respect to the support.

3. In a swivel chair, a tubular support, a supporting rod for the seatarranged in said tubular support so as to be revolvable with respect tothe latter, a ring of stop grooves fixed to the support, a clampingpiece axially adjustable on said supporting rod and having a downwardlyextending jaw, a locking pin provided on said jaw and adapted tocooperate with stop grooves, a helical spring arranged around saidsupporting rod for the seat, said spring having its one end bearingagainst the said ring of stop grooves and its other end engaging thesaid clamping piece for maintaining the locking pin engaged in one ofsaid stop grooves when the seat is not used, said spring beingcompressed upon loading of the seat so that said locking pin isdisengaged from the stop grooves thereby permitting free revolving ofthe seat with respect to its support.

References Cited in the file of this patent UNITED STATES PATENTS

